Global Jet Watch

Abstract:

In this study we predict the total distributions of powerful (FR II) active double-lobed radio galaxies and ghost sources, and their observable distribution in the X-ray sky. We develop an analytic model for the evolution of the lobe emission at radio and X-ray energies. During jet activity, a double radio source emits synchrotron radiation in the radio and X-ray emission due to inverse-Compton (IC) upscattering by gamma~10^3 electrons of the cosmic microwave background. After the jets switch off, the radio luminosity (due to higher gamma electrons) falls faster than the X-ray luminosity and for some time the source appears as an IC ghost of a radio galaxy before becoming completely undetectable in the X-ray. With our model, for one set of typical parameters, we predict radio lobes occupy a volume fraction of the universe of 0.01, 0.03, 0.3 at z=2 (during the quasar era) of the filamentary structures in which they are situated, for typical jet lifetimes 5*10^7 yr, 10^8 yr, 5*10^8 yr; however since the inferred abundance of sources depends on how quickly they fall below the radio flux limit the volume filling factor is found to be a strong function of radio galaxy properties such as energy index and minimum gamma factor of injected particles, the latter not well constrained by observations. We test the predicted number density of sources against the Chandra X-ray Deep Field North survey and also find the contribution to the unresolved cosmic X-ray background by the lobes of radio galaxies. 10-30 per cent of observable double-lobed structures in the X-ray are predicted to be IC ghosts. The derived X-ray luminosity function of our synthetic population shows that double-lobed sources have higher space densities than X-ray clusters at redshifts z>2 and X-ray luminosities above 10^44 erg s^-1.

Abstract:

We present optical spectroscopy of the microquasar SS433 covering a significant fraction of a precessional cycle of its jet axis. The components of the prominent stationary H-alpha and H-beta lines are mainly identified as arising from three emitting regions: (i) a super-Eddington accretion disc wind, in the form of a broad component accounting for most of the mass loss from the system, (ii) a circumbinary disc of material that we presume is being excreted through the binary's L2 point, and (iii) the accretion disc itself as two remarkably persistent components. The accretion disc components move with a Keplerian velocity of ~600 km/s in the outer region of the disc. A direct result of this decomposition is the determination of the accretion disc size, whose outer radius attains ~8 R_sun in the case of Keplerian orbits around a black hole mass of 10 M_sun. We determine an upper limit for the accretion disc inner to outer radius ratio in SS433, R_in/R_out ~ 0.2, independent of the mass of the compact object. The Balmer decrements, H-alpha/H-beta, are extracted from the appropriate stationary emission lines for each component of the system. The physical parameters of the gaseous components are derived. The circumbinary ring decrement seems to be quite constant throughout precessional phase, implying a constant electron density of log N_e(cm^-3) ~ 11.5 for the circumbinary disc. The accretion disc wind shows a larger change in its decrements exhibiting a clear dependence on precessional phase, implying a sinusoid variation in its electron density log N_e(cm^-3) along our line-of-sight between 10 and 13. This dependence of density on direction suggests that the accretion disc wind is polloidal in nature.

Abstract:

New Chandra observations have resolved the structure of the X-ray luminous southern hotspot in the giant radio quasar 4C74.26 into two distinct features. The nearer one to the nucleus is an extremely luminous peak, extended some 5 kpc perpendicular to the orientation of the jet; 19 kpc projected further away from the central nucleus than this is a fainter X-ray arc having similar symmetry. This arc is co-spatial with near-IR and optical emission imaged with Gemini, and radio emission imaged with MERLIN. The angular separation of the double shock structure (itself ~19 kpc or 10 arcsec in size) from the active nucleus which fuels them of ~550 kpc is a reminder of the challenge of connecting "unidentified" hard X-ray or Fermi sources with their origins.